We're not sure what the ZR2 Bison is, but it sounds like it should be awesome.

Update: According to Off-Road.com, the Colorado ZR2 Bison will be a vehicle purpose built for overlanding. Chevy will reportedly team up with American Expedition Vehicles (AEV), which uses a bison as its logo, in creation of the custom truck. The ZR2 Bison was shown to dealers at a recent conference in Las Vegas, and it should be in dealers before the end of the year.

With a 2.8-liter turbodiesel engine producing a modest 186 horsepower (138 kilowatts) and 369 pound-feet (500 Newton-meters) of torque, and a handful of off-road components from massive wheels to a lifted suspension, the ZR2 is the most potent Chevrolet Colorado you can buy today. But it may not be the only rugged option; new patent filings suggest that Chevy could be working on another ZR2 variant.

According to the U.S. Patent and Trademark Office, by way of Autoguide, Chevy has filed a trademark for "Colorado Bison," and "ZR2 Bison" – the latter using the original ZR2 logo with the Bison wordmark underneath. Both filings specify their intended use for "motor land vehicles, namely, trucks" exclusively. It’s unclear exactly what the new nameplate would be for, but we have a few guesses…

Our first guess is a Colorado ZR2 work truck, similar to the prototype we spotted last October. The prototype features all of the same off-road cues you’d expect on a standard ZR2 – bigger wheels, Multimatic shocks, skid plates, etc. – but with the added benefit of a utility bed. Chevy did use that same vehicle for testing the Colorado on Rubicon, but hasn’t said much about the interesting prototype since.

Our second guess – and least likely to happen – is a more powerful version of the ZR2. The current diesel model produces the aforementioned 186 hp and 369 lb-ft of torque, and the V6-powered gas model is more powerful at 308 hp (229 kW) and 275 lb-ft (378 Nm) of torque. It’s hard to imagine a Colorado even more powerful than that, but it’s definitely possible.

Whatever it may be, we’ll have to wait until Chevy officially announces the new nameplate. Hopefully we’ll see it before the end of the year.